During the coming year we plan to complete our work on hormone-inhibited respiratory energy metabolism in senescing Rumex leaf discs. We will be measuring the adenylate energy charge in tissue before and after gibberellin treatment and will also look for a possible direct hormone effect on adenylate transport into isolated mitochondria. The fractionation of chloroplast membrane proteins will be carried out and hormone effects on their degradation and synthesis assessed by radioisotopic methods. Mr. Manos will be conducting measurements of endogenous hormones in relation to cell autolysis in aging attached Rumex obtusifolius leaves. We also plan to complete a study of the interaction of 3 classes of exogenous plant hormones which regulate the rate of chlorophyll breakdown in leaf discs.